From BBC News: New model ‘permits time travel’.
It’s an interesting read. Of course, like most actual scientific articles about time travel, they’re talking about quantum time travel, and not you know…Terminator 2 or anything. But it’s still interesting.
I have no way of comprehending anything related to quantum physics, but I do know logic, and so the problem I have comes in when they start applying this process in terms of actual people traveling backwards in time. Here’s an excerpt:
The researchers say these constraints exist because of the weird laws of quantum mechanics even though, traditionally, they don’t account for a backwards movement in time.
Quantum behaviour is governed by probabilities. Before something has actually been observed, there are a number of possibilities regarding its state. But once its state has been measured those possibilities shrink to one - uncertainty is eliminated.
So, if you know the present, you cannot change it. If, for example, you know your father is alive today, the laws of the quantum universe state that there is no possibility of him being killed in the past.
It is as if, in some strange way, the present takes account of all the possible routes back into the past and, because your father is certainly alive, none of the routes back can possibly lead to his death.
Which is actually an argument I’ve heard many times before. You can’t change the past, because the past has already happened, right? Except of course, that when you’re dealing with people and time travel, unless there’s an artificial means for keeping them from altering the timeline (such as the guides in “A Distant Sound of Thunder”, however ineffective they may have been), there’s nothing to explicitly prevent them from doing so.
But of course, this is all science fiction. Quantum time travel doesn’t have such limitations or larger questions, because it happens on a scale so small that most of us with normal brains can’t begin to comprehend. Still kinda cool to wrap your brain around though, ain’t it?